Folic Acid

Question 1

Failure of closure of the neural tube at the cranial end causes what? At the caudal end?

Answer 1

Cranial: anencephaly - most common and not compatible with life
Caudal: spina bifida - most common

Question 2

Does surgical correction of spina bifida fix the problem?

Answer 2

It fixes the risk of infection, but it does not necessarily affect the motor function?

Question 3

What is the rate of of spina bifida? What is the rate or recurrence?

Answer 3

Rate 1:1000
Recurrence 2%
Recurrence in high risk population 4-5%

Question 4

What ethnicities are at a higher risk? What Canadian geographic area has higher rates?

Answer 4

Welsh
Irish
Sikh
Higher in Atlantic Cnada

Question 5

What is the prenatal screening available for NTD?

How effective is it?

Answer 5

Maternal AFP + US at 15-20 weeks GA

85-90%

Question 6

Are there any other screening options for children considered high risk?
How effective is it?

Answer 6

Amniocentesis for detection of AFP

95%

Question 7

What is the risk of fetal loss associated with amniocentesis?

Answer 7

0.5-1%

Question 8

What are the factors involved in causing a NTD?

Answer 8

Genetics - hence certain ethnicities are involved and recurrence
Folic acid
Meds: valproic acid and CBZ

Question 9

Is there evidence to support folic acid supplementation?

Answer 9

Yes.
Four trials demonstrated a decreased risk of recurrence
All but one of the studies showed that primary prevention with folic acid in the preconception period was effective at decreasing the risk

Question 10

What is the amount of folic acid that is effective for primary prevention and for preventing recurrence?

Answer 10

Primary: 0.4-0.8 mg daily

Prevent recurrence: 0.8 - 4 mg daily

Question 11

How effective is folic acid?

Answer 11

Decreases the risk by 60-70%

Question 12

Are there any other options other than preconception folic acid supplementation? What is the rationale?

Answer 12

Fortification of a food staple: flour

Rationale: half to pregnancies are unplanned, so would not have folic acid supplementation

Question 13

How much folic acid would you need to ingest in a fortified substance? What if you ate tons of it, would there be a risk of toxicity?

Answer 13

0.5 - 1 mg daily

There is no risk of chronic toxicity in people taking up to 10 mg daily

Question 14

Are there risks of folic acid fortification in a food staple

Answer 14

The main risk is for patients with pernicious anaemia (1% in > 60 years) - Vit B12
The folic acid would mask the haematological signs and could worsen the neurological complications - spinal-coord degeneration

Although there are no case reports of this occurring at the doses of fortification

Question 15

So do we recommend food fortification?

Answer 15

The issue is complex and controversial. A big problem s that the target population does not eat a lot of flour.
So, there is insufficient evidence to support the recommendation. Need a big trial over 3 years (evaluated at 18m and 3y)